GRP vs FRP Profiles

Where the terms come from

GRP stands for "Glass Reinforced Plastic", read in some sources as "Glass Reinforced Polyester". The name describes the reinforcement up front: the reinforcement is glass. The term travelled with European engineering literature and is still the default across the UK, Europe and the Gulf; the German GFK (Glasfaserverstärkter Kunststoff) and the North American GRP (Fiber Reinforced Polymer) are its closest equivalents.

FRP stands for Fiber Reinforced Polymer and it spread mainly from North American engineering literature. It says nothing about the type of reinforcement, only that this is "a polymer reinforced with fiber". The fiber may be glass, carbon or aramid — all of them sit under the FRP heading.

So the real difference is not a material difference but a way of describing it difference: GRP names the reinforcement, FRP names the category.

The scope difference in one table

↳ In short: calling a glass-fiber pultruded profile either GRP or FRP is correct. But a carbon-fiber profile cannot be called GRP.

Which term is used where?

In the field the two words sit side by side and often overlap, but there is a pattern. Where composite products arrived through European engineering practice — the UK, continental Europe and the Gulf — the European term settled in, which is why in specifications, tenders and official correspondence GRP has become dominant. In UK and Gulf water and infrastructure work, "GRP pipe", "GRP manhole" and "GRP enclosure" are close to standard usage.

By contrast in export documents, international project specifications and engineering calculation reports FRP comes forward. Catalogs carry both labels — "FRP grating", "FRP ladder" and "FRP profile" on one side, "GRP grating" and "GRP profile" on the other. Today most manufacturers list the same product under both names.

A practical observation: pipes and tanks tend to be called GRP, while grating, handrail and platform products are more often called FRP. That is not a technical distinction; it is a habit formed by the language each product line entered the market with.

So does it make a technical difference?

Between two profiles made from the same glass fiber, the same resin and the same process there is no "one is GRP, the other is FRP" performance gap. What defines the material is not the acronym but the four decisions below:

• Fiber type and content: E-glass or ECR, the fiber content by weight, and how the roving and mat layers are stacked.
• Resin system: polyester; the surface veil and additives are planned around the chemistry, temperature and fire requirement of the environment.
• Section geometry: the same material behaves completely differently as a channel than as an I-beam; wall thickness and moment of inertia change the outcome directly.
• Surface veil and UV protection: the surface veil and UV additive are the invisible detail that sets outdoor service life.

If a supplier tells you "ours is FRP, not GRP, so it is better", the question to ask is obvious: which fiber, which resin, which section? The acronym is not a quality grade.

Which one should you write when asking for a quote?

You can write either one; it makes no difference at our end. What actually decides things is these five pieces of information:

• Service environment: indoors or outdoors, whether there is chemical contact, and whether salt water or constant moisture is involved.
• Section and dimensions: the profile type and h×b×t dimensions; a sketch is even better.
• Length and quantity: the bar length you need and the total meterage.
• Load case: the load to be carried, the span and the deflection expectation.
• Special requirements: color, fire class, electrical insulation requirement, UV exposure.

↳ Do not get stuck on "GRP or FRP?" — tell us the environment and the dimensions and we will build the material around them.

Read on at

If you want to read about the material behind the terms in more detail, the What is a GRP profile? and What is an FRP profile? pages are a good place to start. How both are produced at a constant cross-section is covered on the the pultrusion process page walks through it step by step. If you have not decided which section to start with, the most common structural one, the U channel page has the size table.